Hello,
I know that there are settings in the PS4-menu to deactivate the download and installation of any updates. But now it looks like that this just counts for what the PS4 is doing in rest mode.

As I said, even though it's disabled the console has installed every update so far. Just fear that one day any exploit will be published and directly fixed over night.
Of course it's possible to just unplug it from the internet but as I still use some other online features and I'd like to know if there is any way to block the ports or IP addresses through my router that are related to the ps4 system software.